Large constrictor snake (3)
I believe the answer is:
boa
'large constrictor snake' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for boa that I've seen before include "Snake; feather stole" , "One who puts the squeeze on" , "S American snake that crushes its prey" , "Large constricting snake" , "One with scaly body" .)